JSF Tutorial - JSF Custom Converter Example

We can create our own Custom convertor in JSF.

The following list is the step we can follow to create a custom converter in JSF.

Create a converter class by implementing javax.faces.convert.Converter interface.
Implement getAsObject() and getAsString() methods of above interface.
Use Annotation @FacesConvertor to assign a unique id to the custom convertor.

Example

The following code is from URLConverter.java.

package com.java2s.common;
import javax.faces.application.FacesMessage;
import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.faces.convert.Converter;
import javax.faces.convert.ConverterException;
import javax.faces.convert.FacesConverter;

@FacesConverter("com.java2s.common.URLConverter")
public class URLConverter implements Converter{
  @Override
  public Object getAsObject(FacesContext context, UIComponent component,
      String value) {
    
    String HTTP = "http://";
    StringBuilder url = new StringBuilder();

    if(!value.startsWith(HTTP, 0)){
      url.append(HTTP);
    }
    url.append(value);
    
    if(url.toString().length() > 10){
      FacesMessage msg = 
        new FacesMessage("URL Conversion error.", 
            "Invalid URL format.");
      msg.setSeverity(FacesMessage.SEVERITY_ERROR);
      throw new ConverterException(msg);
    }
    return url.toString();
  }

  @Override
  public String getAsString(FacesContext context, UIComponent component,
      Object value) {

    return value.toString();
    
  }
  
  
}

The following code is from UserBean.java.

package com.java2s.common;


import java.io.Serializable;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.SessionScoped;
 
@ManagedBean(name="user")
@SessionScoped
public class UserBean implements Serializable{
  
  String bookmarkURL;

  public String getBookmarkURL() {
    return bookmarkURL;
  }

  public void setBookmarkURL(String bookmarkURL) {
    this.bookmarkURL = bookmarkURL;
  }

}

The following code is from result.xhtml.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"   
      xmlns:h="http://java.sun.com/jsf/html"
      xmlns:f="http://java.sun.com/jsf/core"
      xmlns:c="http://java.sun.com/jsp/jstl/core"
      >
    <h:body>
      <h:panelGrid columns="2">
      
        Bookmark URL :  
        <h:outputText value="#{user.bookmarkURL}" />
        
      </h:panelGrid>
      
    </h:body>
</html>

The following code is from demo.xhtml.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"   
      xmlns:h="http://java.sun.com/jsf/html"
      xmlns:f="http://java.sun.com/jsf/core"
      >
    <h:body>
    <h:form>
      <h:panelGrid columns="3">
        Enter your bookmark URL :
        <h:inputText id="bookmarkURL" value="#{user.bookmarkURL}" 
          size="20" required="true" label="Bookmark URL">
          <f:converter converterId="com.java2s.common.URLConverter" />
        </h:inputText>
        
        <h:message for="bookmarkURL" style="color:red" />
      
      </h:panelGrid>
      
      <h:commandButton value="Submit" action="result" />
      
    </h:form>
    
    </h:body>
</html>

Download Custom-Converter.zip

To RUN

Copy the generated WAR file from the target folder to Tomcat deployment folder and run Tomcat-Install-folder/bin/startup.bat.

After Tomcat finish starting, type the following URL in the browser address bar.

http://localhost:8080/simple-webapp/demo.xhtml